The present invention relates to an external reinforcement for beams, columns, plates and the like, more particularly a reinforcement which allows to increase the maximum permissible load of existing beams, columns or the like, made of wood, concrete, metal or another material.
It is known that for reinforcing existing constructions, external reinforcements are provided which consist of, for example, a steel sheet, whereby this latter is attached to such construction by means of glue, bolts or the like.
Such known external reinforcement, however, shows the disadvantage that, on one hand, it is very heavy and, on the other hand, it is difficult to attach.
In order to eliminate said disadvantages, already an alternative external reinforcement has been proposed, which reinforcement consists of a plate formed of fibers, such as, for example, carbon fibers, glass fibers or aramide fibers, which are embedded in a resin.
Up to the present, such reinforcement is provided in a continuous process, for example, by pultrusion.
By means of this known technique, it is in fact possible to realize an external reinforcement having a well-defined composition, a very large length, a constant width and thickness, and a smooth surface.
Although such external reinforcement is considerably less heavy and can be provided relatively easy in comparison to external reinforcements consisting of sheets, it shows the considerable disadvantage that all fibers are situated in the longitudinal direction of the plate-shaped reinforcement, such that such plates can take up forces only in their longitudinal direction.
In fact, the forces which in this case are exerted on the fibers are transferred to the surrounding fibers only by means of the resin.
Moreover, it is not possible to drill openings in such known reinforcing plates, in consideration of the fact that this would result in a local interruption of some fibers, such that also the forces exerted on the thus interrupted fibers can not be transferred on the surrounding fibers.
Another disadvantage of the known external reinforcements is that the surface thereof is very smooth as a result of the production method of such plates, as a result of which the adherence thereof on a construction to be reinforced is rather small, such that, in order to improve such adherence, this surface generally is treated with the intention of roughening it, for example, by sandblasting, scouring or treating it in another manner, which, however, is very labour-intensive. Moreover, the fibers may be damaged by such treatment, as a result of which the strength of the reinforcing plate is reduced.
The present invention thus has an external reinforcement as its object which excludes the aforementioned and other disadvantages of the known additional reinforcements and which has as its most important purpose to allow for a better adherence and connection between the external reinforcement and the column, beam or such to be reinforced.
The invention also aims at such external reinforcement which can be realized thicker at the locations where the largest tensile and/or pressing forces occur.
According to the invention, this aim is achieved by an external reinforcement comprising in the combination of fibers and a resin, whereby the majority of the fibers is situated in the longitudinal direction of the reinforcement and whereby at least well-defined portions of the external reinforcement are provided with an additional reinforcement formed by fibers which are arranged according to at least one direction differing from the longitudinal direction of the reinforcement.